An optical waveguide which tapers toward the end thereof is widely known. Such an optical waveguide is widely used when producing near-field light. Utilization of such near-field light is sought after at the time of writing magnetic information. When a recording layer is heated by near-field light, the coercivity of the recording layer decreases. By writing magnetic information into the recording layer with the coercivity thus decreased, it is possible to increase resistance to magnetization within the recording layer against so-called heat fluctuations.